Factor structure and discriminant validity of the SCL-90 in a veteran psychiatric population

This study tested whether the symptom dimension subscales derived for the Symptom Checklist-90 (SCL-90) by factor analysis could be replicated in a new sample. It was administered to 442 veterans undergoing psychiatric treatment at a VA psychiatric outpatient clinic. Factor analysis using the principal-components method yielded a factor structure different from those previously reported for other populations. The first factor extracted, Depression, explained 37% of the variance of the entire instrument, or more than eight times the variance explained by the second factor. Only five of the nine reported SCL-90 symptom subscales emerged in this study; the Anxiety and Psychoticism subscales disappeared, and the Paranoia and Interpersonal Sensitivity subscales merged. In this population the instrument seems to measure a single global distress factor instead of nine independent symptom subscales as reported previously. This finding was corroborated by the fact that depressed, anxious, and schizophrenic patients showed no differences in SCL-90 symptom profile shapes, although they did differ in overall symptom intensity.